Lamp monitoring and control unit and method

ABSTRACT

A unit and method for remotely monitoring and/or controlling an apparatus and specifically for remotely monitoring and/or controlling street lamps. The lamp monitoring and control unit comprises a processing and sensing unit for sensing at least one lamp parameter of an associated lamp, and for processing the lamp parameter to monitor and control the associated lamp by outputting monitoring data and control information, and a transmit unit for transmitting the monitoring data, representing the at least one lamp parameter, from the processing and sensing unit. The method for monitoring and controlling a lamp comprises the steps of: sensing at least one lamp parameter of an associated lamp; processing the at least one lamp parameter to produce monitoring data and control information; transmitting the monitoring data; and applying the control information.

This application is a Continuation of Ser. No. 11/117,518, filed Apr.29, 2005 (now U.S. Pat. No. 7,113,893), which is a Continuation of Ser.No. 10/811,855, filed Mar. 30, 2004 (now U.S. Pat. No. 6,889,174), whichis a Continuation of Ser. No. 10/251,756, filed Sep. 23, 2002 (now U.S.Pat. No. 6,714,895), which is a Continuation of Ser. No. 09/605,027,filed Jun. 28, 2000 (now U.S. Pat. No. 6,456,960), which is a Divisionalof Ser. No. 09/501,274, filed Feb. 9, 2000 (now U.S. Pat. No.6,393,381), which is a Divisional of Ser. No. 08/838,302, filed Apr. 16,1997 (now U.S. Pat. No. 6,119,076). The entire disclosure of the priorapplications is considered as being part of the disclosure of theaccompanying application and is hereby incorporated by referencetherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a unit and method for remotelymonitoring and/or controlling an apparatus and specifically to a lampmonitoring and control unit and method for use with street lamps.

2. Background of the Related Art

The first street lamps were used in Europe during the latter half of theseventeenth century. These lamps consisted of lanterns which wereattached to cables strung across the street so that the lantern hungover the center of the street. In France, the police were responsiblefor operating and maintaining these original street lamps while inEngland contractors were hired for street lamp operation andmaintenance. In all instances, the operation and maintenance of streetlamps was considered a government function.

The operation and maintenance of street lamps, or more generally anyunits which are distributed over a large geographic area, can be dividedinto two tasks: monitor and control. Monitoring comprises thetransmission of information from the distributed unit regarding theunit's status and controlling comprises the reception of information bythe distributed unit.

For the present example in which the distributed units are street lamps,the monitoring function comprises periodic checks of the street lamps todetermine if they are functioning properly. The controlling functioncomprises turning the street lamps on at night and off during the day.

This monitor and control function of the early street lamps was verylabor intensive since each street lamp had to be individually lit(controlled) and watched for any problems (monitored). Because theseearly street lamps were simply lanterns, there was no centralizedmechanism for monitor and control and both of these functions weredistributed at each of the street lamps.

Eventually, the street lamps were moved from the cables hanging over thestreet to poles which were mounted at the side of the street.Additionally, the primitive lanterns were replaced with oil lamps.

The oil lamps were a substantial improvement over the original lanternsbecause they produced a much brighter light. This resulted inillumination of a greater area by each street lamp. Unfortunately, thesestreet lamps still had the same problem as the original lanterns in thatthere was no centralized monitor and control mechanism to light thestreet lamps at night and watch for problems.

In the 1840's, the oil lamps were replaced by gaslights in France. Theadvent of this new technology began a government centralization of aportion of the control function for street lighting since the gas forthe lights was supplied from a central location.

In the 1880's, the gaslights were replaced with electrical lamps. Theelectrical power for these street lamps was again provided from acentral location. With the advent of electrical street lamps, thegovernment finally had a centralized method for controlling the lamps bycontrolling the source of electrical power.

The early electrical street lamps were composed of arc lamps in whichthe illumination was produced by an arc of electricity flowing betweentwo electrodes.

Currently, most street lamps still use arc lamps for illumination. Themercury-vapor lamp is the most common form of street lamp in use today.In this type of lamp, the illumination is produced by an arc which takesplace in a mercury vapor.

FIG. 1 shows the configuration of a typical mercury-vapor lamp. Thisfigure is provided only for demonstration purposes since there are avariety of different types of mercury-vapor lamps.

The mercury-vapor lamp consists of an arc tube 110 which is filled withargon gas and a small amount of pure mercury. Arc tube 110 is mountedinside a large outer bulb 120 which encloses and protects the arc tube.Additionally, the outer bulb may be coated with phosphors to improve thecolor of the light emitted and reduce the ultraviolet radiation emitted.Mounting of arc tube 110 inside outer bulb 120 may be accomplished withan arc tube mount support 130 on the top and a stem 140 on the bottom.

Main electrodes 150 a and 150 b, with opposite polarities, aremechanically sealed at both ends of arc tube 110. The mercury-vapor lamprequires a sizeable voltage to start the arc between main electrodes 150a and 150 b.

The starting of the mercury-vapor lamp is controlled by a startingcircuit (not shown in FIG. 1) which is attached between the power source(not shown in FIG. 1) and the lamp. Unfortunately, there is no standardstarting circuit for mercury-vapor lamps. After the lamp is started, thelamp current will continue to increase unless the starting circuitprovides some means for limiting the current. Typically, the lampcurrent is limited by a resistor, which severely reduces the efficiencyof the circuit, or by a magnetic device, such as a choke or atransformer, called a ballast.

During the starting operation, electrons move through a startingresistor 160 to a starting electrode 170 and across a short gap betweenstarting electrode 170 and main electrode 150 b of opposite polarity.The electrons cause ionization of some of the Argon gas in the arc tube.The ionized gas diffuses until a main arc develops between the twoopposite polarity main electrodes 150 a and 150 b. The heat from themain arc vaporizes the mercury droplets to produce ionized currentcarriers. As the lamp current increases, the ballast acts to limit thecurrent and reduce the supply voltage to maintain stable operation andextinguish the arc between main electrode 150 b and starting electrode170.

Because of the variety of different types of starter circuits, it isvirtually impossible to characterize the current and voltagecharacteristics of the mercury-vapor lamp. In fact, the mercury-vaporlamp may require minutes of warm-up before light is emitted.Additionally, if power is lost, the lamp must cool and the mercurypressure must decrease before the starting arc can start again.

The mercury-vapor lamp has become the predominant street lamp withmillions of units produced annually. The current installed base of thesestreet lamps is enormous with more than 500,000 street lamps in LosAngeles alone. The mercury-vapor lamp is not the most efficient gaseousdischarge lamp, but is preferred for use in street lamps because of itslong life, reliable performance, and relatively low cost.

Although the mercury-vapor lamp has been used as a common example ofcurrent street lamps, there is increasing use of other types of lampssuch as metal halide and high pressure sodium. All of these types oflamps require a starting circuit which makes it virtually impossible tocharacterize the current and voltage characteristics of the lamp.

FIG. 2 shows a lamp arrangement 201 with a typical lamp sensor unit 210which is situated between a power source 220 and a lamp assembly 230.Lamp assembly 230 includes a lamp 240 (such as the mercury-vapor lamppresented in FIG. 1) and a starting circuit 250.

Most cities currently use automatic lamp control units to control thestreet lamps. These lamp control units provide an automatic, butdecentralized, control mechanism for turning the street lamps on atnight and off during the day.

A typical street lamp assembly 201 includes a lamp sensor unit 210 whichin turn includes a light sensor 260 and a relay 270 as shown in FIG. 2.Lamp sensor unit 210 is electrically coupled between external powersource 220 and starting circuit 250 of lamp assembly 230. There is a hotline 280 a and a neutral line 280 b providing electrical connectionbetween power source 220 and lamp sensor unit 210. Additionally, thereis a switched line 280 c and a neutral line 280 d providing electricalconnection between lamp sensor unit 210 and starting circuit 250 of lampassembly 230.

From a physical standpoint, most lamp sensor units 210 use a standardthree prong plug, for example a twist lock plug, to connect to the backof lamp assembly 230. The three prongs couple to hot line 280 a,switched line 280 c, and neutral lines 280 b and 280 d. In other words,the neutral lines 280 b and 280 d are both connected to the samephysical prong since they are at the same electrical potential. Somesystems also have a ground wire, but no ground wire is shown in FIG. 2since it is not relevant to the operation of lamp sensor unit 210.

Power source 220 may be a standard 115 Volt, 60 Hz source from a powerline. Of course, a variety of alternatives are available for powersource 220. In foreign countries, power source 220 may be a 220 Volt, 50Hz source from a power line. Additionally, power source 220 may be a DCvoltage source or, in certain remote regions, it may be a battery whichis charged by a solar reflector.

The operation of lamp sensor unit 210 is fairly simple. At sunset, whenthe light from the sun decreases below a sunset threshold, the lightsensor 260 detects this condition and causes relay 270 to close. Closureof relay 270 results in electrical connection of hot line 280 a andswitched line 280 c with power being applied to starting circuit 250 oflamp assembly 230 to ultimately produce light from lamp 240. At sunrise,when the light from the sun increases above a sunrise threshold, lightsensor 260 detects this condition and causes relay 270 to open. Openingof relay 270 eliminates electrical connection between hot line 280 a andswitched line 280 c and causes the removal of power from startingcircuit 250 which turns lamp 240 off.

Lamp sensor unit 210 provides an automated, distributed controlmechanism to turn lamp assembly 230 on and off. Unfortunately, itprovides no mechanism for centralized monitoring of the street lamp todetermine if the lamp is functioning properly. This problem isparticularly important in regard to the street lamps on major boulevardsand highways in large cities. When a street lamp burns out over ahighway, it is often not replaced for a long period of time because themaintenance crew will only schedule a replacement lamp when someonecalls the city maintenance department and identifies the exact polelocation of the bad lamp. Since most automobile drivers will not stop onthe highway just to report a bad street lamp, a bad lamp may gounreported indefinitely.

Additionally, if a lamp is producing light but has a hidden problem,visual monitoring of the lamp will never be able to detect the problem.Some examples of hidden problems relate to current, when the lamp isdrawing significantly more current than is normal, or voltage, when thepower supply is not supplying the appropriate voltage level to thestreet lamp.

Furthermore, the present system of lamp control in which an individuallight sensor is located at each street lamp, is a distributed controlsystem which does not allow for centralized control. For example, if thecity wanted to turn on all of the street lamps in a certain area at acertain time, this could not be done because of the distributed natureof the present lamp control circuits.

Because of these limitations, a new type of lamp control unit is neededwhich allows centralized monitoring and/or control of the street lampsin a geographical area.

One attempt to produce a centralized control mechanism is a productcalled the RadioSwitch made by Cetronic. The RadioSwitch is a remotelycontrolled time switch for installation on the DIN-bar of control units.It is used for remote control of electrical equipment via local ornational paging networks. Unfortunately, the RadioSwitch is unable toaddress most of the problems listed above.

Since the RadioSwitch is receive only (no transmit capability), it onlyallows one to remotely control external equipment. Furthermore, sincethe communication link for the RadioSwitch is via paging networks, it isunable to operate in areas in which paging does not exist (for example,large rural areas in the United States). Additionally, although theRadioSwitch can be used to control street lamps, it does not use thestandard three prong interface used by the present lamp control units.Accordingly, installation is difficult because it cannot be used as aplug-in replacement for the current lamp control units.

Because of these limitations of the available equipment, there exists aneed for a new type of lamp control unit which allows centralizedmonitoring and/or control of the street lamps in a geographical area.More specifically, this new device must be inexpensive, reliable, andeasy to install in place of the millions of currently installed lampcontrol units.

Although the above discussion has presented street lamps as an example,there is a more general need for a new type of monitoring and controlunit which allows centralized monitoring and/or control of unitsdistributed over a large geographical area.

The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY OF THE INVENTION

The present invention provides a lamp monitoring and control unit andmethod for use with street lamps which solves the problems describedabove.

While the invention is described with respect to use with street lamps,it is more generally applicable to any application requiring centralizedmonitoring and/or control of units distributed over a large geographicalarea.

These and other objects, advantages and features can be accomplished inaccordance with the present invention by the provision of a lampmonitoring and control unit comprising: a processing and sensing unitfor sensing at least one lamp parameter of an associated lamp, and forprocessing the at least one lamp parameter to monitor and control theassociated lamp by outputting monitoring data and control information;and a transmit unit for transmitting the monitoring data, representingthe at least one lamp parameter, from the processing and sensing unit.

These and other objects, advantages and features can also be achieved inaccordance with the invention by a lamp monitoring and control unitcomprising: a processing unit for processing at least one lamp parameterand outputting a relay control signal; a light sensor, coupled to theprocessing unit, for sensing an amount of ambient light, producing alight signal associated with the amount of ambient light, and outputtingthe light signal to the processing unit; a relay for switching aswitched power line to a hot power line based upon the relay controlsignal from the processing unit; a voltage sensor, coupled to theprocessing unit, for sensing a switched voltage in the switched powerline; a current sensor, coupled to the switched power line, for sensinga switched current in the switched power line; and a transmit unit fortransmitting monitoring data, representing the at least one lampparameter, from the processing unit.

These and other objects, advantages and features can also be achieved inaccordance with the invention by a method for monitoring and controllinga lamp comprising the steps of: sensing at least one lamp parameter ofan associated lamp; processing the at least one lamp parameter toproduce monitoring data and control information; transmitting themonitoring data; and applying the control information.

A feature of the present invention is that the lamp monitoring andcontrol unit may be coupled to the associated lamp via a standard threeprong plug.

Another feature of the present invention is that the processing andsensing unit may include a relay for switching the switched power lineto the hot power line.

Another feature of the present invention is that the processing andsensing unit may include a current sensor for sensing a switched currentin the switched power line.

Another feature of the present invention is that the processing andsensing unit may include a voltage sensor for sensing a switched voltagein the switched power line.

Another feature of the present invention is that the transmit unit mayinclude a transmitter and a modified directional discontinuity ringradiator, and the modified directional discontinuity ring radiator mayinclude a plurality of loops for resonance at a desired frequency range.

Another feature of the present invention is that in accordance with anembodiment of the method, the step of processing may include providingan initial delay, a current stabilization delay, a relay settle delay,to prevent false triggering.

Another feature of the present invention is that in accordance with anembodiment of the method, the step of transmitting the monitoring datamay include a pseudo-random reporting start time delay, reporting deltatime, and frequency. The pseudo-random nature of these values may bebased on the serial number of the lamp monitoring and control unit.

An advantage of the present invention is that it solves the problem ofproviding centralized monitoring and/or control of the street lamps in ageographical area.

Another advantage of the present invention is that by using the standardthree prong plug of the current street lamps, it is easy to install inplace of the millions of currently installed lamp control units.

An additional advantage of the present invention is that it provides fora new type of monitoring and control unit which allows centralizedmonitoring and/or control of units distributed over a large geographicalarea.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 shows the configuration of a typical mercury-vapor lamp.

FIG. 2 shows a typical configuration of a lamp arrangement comprising alamp sensor unit situated between a power source and a lamp assembly.

FIG. 3 shows a lamp arrangement, according to one embodiment of theinvention, comprising a lamp monitoring and control unit situatedbetween a power source and a lamp assembly.

FIG. 4 shows a lamp monitoring and control unit, according to anotherembodiment of the invention, including a processing and sensing unit, aTx unit, and an Rx unit.

FIG. 5 shows a lamp monitoring and control unit, according to anotherembodiment of the invention, including a processing and sensing unit, aTx unit, an Rx unit, and a light sensor.

FIG. 6 shows a lamp monitoring and control unit, according to anotherembodiment of the invention, including a processing and sensing unit, aTx unit, and a light sensor.

FIG. 7 shows a lamp monitoring and control unit, according to anotherembodiment of the invention, including a microprocessing unit, an A/Dunit, a current sensing unit, a voltage sensing unit, a relay, a Txunit, and a light sensor.

FIG. 8 shows an example frequency channel plan for a lamp monitoring andcontrol unit, according to another embodiment of the invention.

FIG. 9 shows a typical directional discontinuity ring radiator (DDRR)antenna.

FIG. 10 shows a modified DDRR antenna, according to another embodimentof the invention.

FIGS. 11A-E show methods for one implementation of logic for a lampmonitoring and control unit, according to another embodiment of theinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiments of a lamp monitoring and control unit (LMCU)and method, which allows centralized monitoring and/or control of streetlamps, will now be described with reference to the accompanying figures.While the invention is described with reference to an LMCU, theinvention is not limited to this application and can be used in anyapplication which requires a monitoring and control unit for centralizedmonitoring and/or control of devices distributed over a largegeographical area. Additionally, the term street lamp in this disclosureis used in a general sense to describe any type of street lamp, arealamp, or outdoor lamp.

FIG. 3 shows a lamp arrangement 301 which includes lamp monitoring andcontrol unit 310, according to one embodiment of the invention. Lampmonitoring and control unit 310 is situated between a power source 220and a lamp assembly 230. Lamp assembly 230 includes a lamp 240 and astarting circuit 250.

Power source 220 may be a standard 115 volt, 60 Hz source supplied by apower line. It is well known to those skilled in the art that a varietyof alternatives are available for power source 220. In foreigncountries, power source 220 may be a 220 volt, 50 Hz source from a powerline. Additionally, power source 220 may be a DC voltage source or, incertain remote regions, it may be a battery which is charged by a solarreflector.

Recall that lamp sensor unit 210 included a light sensor 260 and a relay270 which is used to control lamp assembly 230 by automaticallyswitching the hot power 280 a to a switched power line 280 c dependingon the amount of ambient light received by light sensor 260.

On the other hand, lamp monitoring and control unit 310 provides severalfunctions including a monitoring function which is not provided by lampsensor unit 210. Lamp monitoring and control unit 310 is electricallylocated between the external power supply 220 and starting circuit 250of lamp assembly 230. From an electrical standpoint, there is a hot 280a with a neutral 280 b electrical connection between power supply 220and lamp monitoring and control unit 310. Additionally, there is aswitched 280 c and a neutral 280 d electrical connection between lampmonitoring and control unit 310 and starting circuit 250 of lampassembly 230.

From a physical standpoint, lamp monitoring and control unit 310 may usea standard three-prong plug to connect to the back of lamp assembly 230.The three prongs in the standard three-prong plug represent hot 280 a,switched 280 c, and neutral 280 b and 280 d. In other words, the neutrallines 280 b and 280 d are both connected to the same physical prong andshare the same electrical potential.

Although use of a three-prong plug is recommended because of thesubstantial number of street lamps using this type of standard plug, itis well known to those skilled in the art that a variety of additionaltypes of electrical connection may be used for the present invention.For example, a standard power terminal block or AMP power connector maybe used.

FIG. 4 shows lamp monitoring and control unit 310, according to anotherembodiment of the invention. Lamp monitoring and control unit 310includes a processing and sensing unit 412, a transmit (TX) unit 414,and an optional receive (RX) unit 416. Processing and sensing unit 412is electrically connected to hot 280 a, switched 280 c, and neutral 280b and 280 d electrical connections. Furthermore, processing and sensingunit 412 is connected to TX unit 414 and RX unit 416. In a standardapplication, TX unit 414 may be used to transmit monitoring data and RXunit 416 may be used to receive control information. For applications inwhich external control information is not required, RX unit 416 may bedeleted from lamp monitoring and control unit 310.

FIG. 5 shows a lamp monitoring and control unit 310, according toanother embodiment of the invention, with a configuration similar tothat shown in FIG. 4. Here, however, lamp monitoring and control unit310 of FIG. 5 further includes a light sensor 518, analogous to lightsensor 216 of FIG. 2, which allows for some degree of local control.Light sensor 518 is coupled to processing and sensing unit 412 toprovide information regarding the level of ambient light. Accordingly,processing and sensing unit 412 may receive control information eitherlocally from light sensor 518 or remotely from RX unit 416.

FIG. 6 shows another configuration for lamp monitoring control unit 310,according to another embodiment of the invention, but without RX unit416. This embodiment of lamp monitoring and control unit 310 can be usedin applications in which only local control information, for examplefrom light sensor 518, is to be passed to processing and sensing unit412. In other words, remote monitoring data may be received via TX unit414 and local control information may be generated via light sensor 518.

FIG. 7 shows a more detailed implementation of lamp monitoring andcontrol unit 310 of FIG. 6, according to one embodiment of theinvention.

FIG. 7 shows one embodiment of a lamp monitoring and control unit 310with a three-prong plug 720 to provide hot 280 a, neutral 280 b and 280d, and switched 280 c electrical connections. The hot 280 a and neutral280 b and 280 d electrical connections are connected to an optionalswitching power supply 710 in applications in which AC power is inputand DC power is required to power the circuit components of lampmonitoring and control unit 310.

Light sensor 518 includes a photosensor 518 a and associated lightsensor circuitry 518 b. TX unit 414 includes a radio modem transmitter414 a and a built-in antenna 414 b. Processing and sensing unit 412includes microprocessor circuitry 412 a, a relay 412 b, current andvoltage sensing circuitry 412 c, and an analog-to-digital converter 412d.

Microprocessor circuitry 412 a includes any standardmicroprocessor/microcontroller such as the Intel 8751 or Motorola68HC16. Additionally, in applications in which cost is an issue,microprocessor circuitry 412 a may comprise a small, low cost processorwith built-in memory such as the Microchip PIC 8 bit microcontroller.Furthermore, microprocessor circuitry 412 a may be implemented by usinga PAL, EPLD, FPGA, or ASIC device.

Microprocessor circuitry 412 a receives and processes input signals andoutputs control signals. For example, microprocessor circuitry 412 areceives a light sensing signal from light sensor 518. This lightsensing signal may either be a threshold indication signal, that is,providing a digital signal, or some form of analog signal.

Based upon the value of the light sensing signal, microprocessorcircuitry 412 a may alternatively or additionally execute software tooutput a relay control signal to a relay 412 a which switches switchedpower line 280 c to hot power line 280 a.

Microprocessor circuitry 412 a may also interface to other sensingcircuitry. For example, the lamp monitoring and control unit 310 mayinclude current and voltage sensing circuitry 412 c which senses thevoltage of the switched power line 280 c and also senses the currentflowing through the switched power line 280 c. The voltage sensingoperation may produce a voltage ON signal which is sent from the currentand voltage sensing circuitry 412 c to microprocessor circuitry 412 a.This voltage ON signal can be of a threshold indication, that is, someform of digital signal, or it can be an analog signal.

Current and voltage sensing circuitry 412 c can also output a currentlevel signal indicative of the amount of current flowing throughswitched power line 280 c. The current level signal can interfacedirectly to microprocessor circuitry 412 a or, alternatively, it can becoupled to microprocessing circuitry 412 a through an analog-to-digitalconverter 412 b. Microprocessor circuitry 412 a can produce a CLOCKsignal which is sent to analog-to-digital converter 412 d and which isused to allow A/D data to pass from analog-to-digital converter 412 d tomicroprocessor circuitry 412 a.

Microprocessor circuitry 412 a can also be coupled to radio modemtransmitter 414 a to allow monitoring data to be sent from lampmonitoring control unit 310.

The configuration shown in FIG. 7 is intended as an illustration of oneway in which the present invention can be implemented. For example,analog-to-digital converter 412 b may be combined into microprocessorcircuitry 412 a for some applications. Furthermore, the memory formicroprocessor circuitry 412 a may either be internal to themicroprocessor circuitry or contained as an external EPROM, EEPROM,Flash RAM, dynamic RAM, or static RAM. Current and voltage sensorcircuitry 412 c may either be combined in one unit with sharedcomponents or separated into two separate units. Furthermore, thecurrent sensing portion of current and voltage sensing circuitry 412 cmay include a current sensing transformer 413 and associated circuitryas shown in FIG. 7 or may be configured using different circuitry whichalso senses current.

The frequencies to be used by the TX unit 414 are selected bymicroprocessor circuitry 412 a. There are a variety of ways that thesefrequencies can be organized and used, examples of which will bediscussed below.

FIG. 8 shows an example of a frequency channel plan for lamp monitoringand control unit 310, according to one embodiment of the invention. Inthis example table, interactive video and data service (IVDS) radiofrequencies in the range of 218-219 MHz are shown. The IVDS channels inFIG. 8 are divided into two groups, Group A and Group B, with each grouphaving nineteen channels spaced at 25 KHz steps. The first channel ofthe group A frequencies is located at 218.025 MHz and the first channelof the group B frequencies is located at 218.525 MHz.

The mapping between channel numbers and frequencies can either beperformed in microprocessor circuitry 412 a or TX unit 414. In otherwords the data signal sent to TX unit 414 from microprocessor circuitry412 a may either consist of channel numbers or frequency data. Totransmit at these frequencies, TX unit 414 must have an associatedantenna 414 b.

FIG. 9 shows a typical directional discontinuity ring radiator (DDRR)antenna 900. DDRR antenna 900 is well known to those skilled in the art,and detailed description of the operation and use of this antenna can befound in the American Radio Relay League (ARRL) Handbook, theappropriate sections of which are incorporated by reference. The problemwith using DDRR antenna 900 in applications such as lamp monitoring andcontrol unit 310 is that the antenna dimension for resonance in certainfrequency ranges, such as the IVDS frequency range, is too large.

FIG. 10 shows a modified DDRR antenna 1000, according to a furtherembodiment of the invention. Modified DDRR antenna 1000 is mounted on aPC board 1010 and includes a metal shield 1020, a coil segment 1060, alooped wire coil 1040, a first variable capacitor C1, and a secondvariable capacitor C2. Additionally, a plastic assembly (not shown) maybe included in modified DDRR antenna 1000 to hold looped wire coil 1040in place.

The RF energy to be radiated is fed into an RF feed point 1050 andtravels through wire segment 1060 through a hole 1030 in metal shield1020 to variable capacitor C2. Variable capacitor C2 is used to matchthe input impedance of modified DDRR antenna 1000 to 50 ohms. Loopedwire coil 1040 is looped several times, as opposed to typical DDRRantenna 900 which only has one loop. Looped wire coil 1040 may becoupled to wire segment 1060, or both looped wire coil 1040 and wiresegment 1060 may be part of a continuous piece of wire, as shown. Theend of wire coil 1040 is coupled to capacitor C1 which tunes modifiedDDRR antenna 1000 for resonance at the desired frequency.

Modified DDRR antenna 1000 has multiple loops in wire coil 1040 whichallow the antenna to resonate at particular frequencies. For example, iftypical DDRR antenna 900 with approximately a 5″ diameter is modified toinclude three to six loops, then the diameter can be decreased to lessthan 4″ and still resonate in the IVDS frequency range. In other words,if typical DDRR antenna 900 has a 4″ diameter, it will have poorresonance in the IVDS frequency range. In contrast, if modified DDRRantenna 1000 has a 4″ diameter, it will have excellent resonance in theIVDS frequency range. Accordingly, modified DDRR antenna 1000 providesfor an efficient transformation of input RF energy for radiation as anE-M field because of its improved resonance at the desired frequenciesand an impedance match (such as 50 ohms) to the input RF source. Theexact number of additional loops and spacing for modified DDRR antenna1000 depends on the frequency range selected.

Furthermore, if lamp monitoring and control unit 310 includes RX unit416, as shown in FIG. 4, modified DDRR antenna 1000 can be shared by TXunit 414 and RX unit 416. Alternatively, RX unit 416 and TX unit 414 mayuse separate antennas.

FIGS. 11A-E show methods for implementation of logic for lamp monitoringand control unit 310, according to a further embodiment of theinvention. These methods may be implemented in a variety of ways,including software in microprocessor circuitry 412 a or customized logicchips.

FIG. 11A shows one method for energizing and de-energizing a street lampand transmitting associated monitoring data. The method of FIG. 11Ashows a single transmission for each control event. The method beginswith a start block 1100 and proceeds to step 1110 which involveschecking AC and Daylight Status. The Check AC and Daylight Status step1110 is used to check for conditions where the AC power and/or theDaylight Status have changed. If a change does occur, the methodproceeds to the step 1120 which is a decision block based on the change.

If a change occurred, step 1120 proceeds to a Debounce Delay step 1122which involves inserting a Debounce Delay. For example, the DebounceDelay may be 0.5 seconds. After Debounce Delay step 1122, the methodleads back to Check AC and Daylight Status step 1110.

If no change occurred, step 1120 proceeds to step 1130 which is adecision block to determine whether the lamp should be energized. If thelamp should be energized, then the method proceeds to step 1132 whichturns the lamp on. After step 1132 when the lamp is turned on, themethod proceeds to step 1134 which involves Current Stabilization Delayto allow the current in the street lamp to stabilize. The amount ofdelay for current stabilization depends upon the type of lamp used.However, for a typical vapor lamp a ten minute stabilization delay isappropriate. After step 1134, the method leads back to step 1110 whichchecks AC and Daylight Status.

Returning to step 1130, if the lamp is not to be energized, then themethod proceeds to step 1140 which is a decision block to check todeenergize the lamp. If the lamp is to be deenergized, the methodproceeds to step 1142 which involves turning the Lamp Off. After thelamp is turned off, the method proceeds to step 1144 in which the relayis allowed a Settle Delay time. The Settle Delay time is dependent uponthe particular relay used and may be, for example, set to 0.5 seconds.After step 1144, the method returns to step 1110 to check the AC andDaylight Status.

Returning to step 1140, if the lamp is not to be deenergized, the methodproceeds to step 1150 in which an error bit is set, if required andproceeds to step 1160 in which an A/D is read. For example, the A/D maybe the analog-to-digital converter 412 d for reading the current levelas shown in FIG. 7.

The method then proceeds from step 1160 to step 1170 which checks to seeif a transmit is required. If no transmit is required, the methodproceeds to step 1172 in which a Scan Delay is executed. The Scan Delaydepends upon the circuitry used and, for example, may be 0.5 seconds.After step 1172, the method returns to step 1110 which checks AC andDaylight Status.

Returning to step 1170, if a transmit is required, then the methodproceeds to step 1180 which performs a transmit operation. After thetransmit operation of step 1180 is completed, the method then returns tostep 1110 which checks AC and Daylight Status.

FIG. 11B is analogous to FIG. 11A with one modification. Thismodification occurs after step 1120. If a change has occurred, ratherthan simply executing step 1122, the Debounce Delay, the method performsa further step 1124 which involves checking whether daylight hasoccurred. If daylight has not occurred, then the method proceeds to step1126 which executes an Initial Delay. This initial delay may be, forexample, 0.5 seconds. After step 1126, the method proceeds to step 1122and follows the same method as shown in FIG. 11A.

Returning to step 1124 which involves checking whether daylight hasoccurred, if daylight has occurred, the method proceeds to step 1128which executes an Initial Delay. The Initial Delay associated with step1128 should be a significantly larger value than the Initial Delayassociated with step 1126. For example, an Initial Delay of 45 secondsmay be used. The Initial Delay of step 1128 is used to prevent a falsetriggering which deenergizes the lamp. In actual practice, this extendeddelay can become very important because if the lamp is inadvertentlydeenergized too soon, it requires a substantial amount of time toreenergize the lamp (for example, ten minutes). After step 1128, themethod proceeds to step 1122 which executes a Debounce Delay and thenreturns to step 1110 as shown in FIGS. 11A and 11B.

FIG. 11C shows a method for transmitting monitoring data multiple timesin a lamp monitoring and control unit, according to a further embodimentof the invention. This method is particularly important in applicationsin which lamp monitoring and control unit 310 does not have a RX unit416 for receiving acknowledgements of transmissions.

The method begins with a transmit start block 1182 and proceeds to step1184 which involves initializing a count value, i.e. setting the countvalue to zero. Step 1184 proceeds to step 1186 which involves setting avariable x to a value associated with a serial number of lamp monitoringand control unit 310. For example, variable x may be set to 50 times thelowest nibble of the serial number.

Step 1186 proceeds to step 1188 which involves waiting a reporting starttime delay associated with the value x. The reporting start time is theamount of delay time before the first transmission. For example, thisdelay time may be set to x seconds where x is an integer between 1 and32,000 or more. This example range for x is particularly useful in thestreet lamp application since it distributes the packet reporting starttimes over more than eight hours, approximately the time from sunset tosunrise.

Step 1188 proceeds to step 1190 in which a variable y representing achannel number is set. For example, y may be set to the integer value ofRTC/12.8, where RTC represents a real time clock counting from 0-255 asfast as possible. The RTC may be included in microprocessing circuitry412 a.

Step 1190 proceeds to step 1192 in which a packet is transmitted onchannel y. Step 1192 proceeds to step 1194 in which the count value isincremented. Step 1194 proceeds to step 1196 which is a decision blockto determine if the count value equals an upper limit N.

If the count is not equal to N, step 1196 returns to step 1188 and waitsanother delay time associated with variable x. This delay time is thereporting delta time since it represents the time difference between twoconsecutive reporting events.

If the count is equal to N, step 1196 proceeds to step 1198 which is anend block. The value for N must be determined based on the specificapplication. Increasing the value of N decreases the probability of aunsuccessful transmission since the same data is being sent multipletimes and the probability of all of the packets being lost decreases asN increases. However, increasing the value of N increases the amount oftraffic which may become an issue in a lamp monitoring and controlsystem with a plurality of lamp monitoring and control units.

FIG. 11D shows a method for transmitting monitoring data multiple timesin a monitoring and control unit according to a another embodiment ofthe invention.

The method begins with a transmit start block 1110′ and proceeds to step1112′ which involves initializing a count value, i.e., setting the countvalue to 1. The method proceeds from step 1112′ to step 1114′ whichinvolves randomizing the reporting start time delay. The reporting starttime delay is the amount of time delay required before the transmissionof the first data packet. A variety of methods can be used for thisrandomization process such as selecting a pseudo-random value or basingthe randomization on the serial number of monitoring and control unit510.

The method proceeds from step 1114′ to step 1116′ which involveschecking to see if the count equals 1. If the count is equal to 1, thenthe method proceeds to step 1120′ which involves setting a reportingdelta time equal to the reporting start time delay. If the count is notequal to 1, the method proceeds to step 1118′ which involves randomizingthe reporting delta time. The reporting delta time is the difference intime between each reporting event. A variety of methods can be used forrandomizing the reporting delta time including selecting a pseudo-randomvalue or selecting a random number based upon the serial number of themonitoring and control unit 510.

After either step 1118′ or step 1120′, the method proceeds to step 1122′which involves randomizing a transmit channel number. The transmitchannel number is a number indicative of the frequency used fortransmitting the monitoring data. There are a variety of methods forrandomizing the transmit channel number such as selecting apseudo-random number or selecting a random number based upon the serialnumber of the monitoring and control unit 510.

The method proceeds from step 1122′ to step 1124′ which involves waitingthe reporting delta time. It is important to note that the reportingdelta time is the time which was selected during the randomizationprocess of step 1118′ or the reporting start time delay selected in step1114′, if the count equals 1. The use of separate randomization steps1114′ and 1118′ is important because it allows the use of differentrandomization functions for the reporting start time delay and thereporting delta time, respectively.

After step 1124′ the method proceeds to step 1126′ which involvestransmitting a packet on the transmit channel selected in step 1122′.

The method proceeds from step 1126′ to step 1128′ which involvesincrementing the counter for the number of packet transmissions.

The method proceeds from step 1128′ to step 1130′ in which the count iscompared with a value N which represents the maximum number oftransmissions for each packet. If the count is less than or equal to N,then the method proceeds from step 1130′ back to step 1118′ whichinvolves randomizing the reporting delta time for the next transmission.If the count is greater than N, then the method proceeds from step 1130′to the end block 1132′ for the transmission method.

In other words, the method will continue transmission of the same packetof data N times, with randomization of the reporting start time delay,randomization of the reporting delta times between each reporting event,and randomization of the transmit channel number for each packet. Thesemultiple randomizations help stagger the packets in the frequency andtime domain to reduce the probability of collisions of packets fromdifferent monitoring and control units.

FIG. 11E shows a further method for transmitting monitoring datamultiple times from a monitoring and control unit 510, according toanother embodiment of the invention.

The method begins with a transmit start block 1140′ and proceeds to step1142′ which involves initializing a count value, i.e., setting the countvalue to 1. The method proceeds from step 1142′ to step 1144′ whichinvolves reading an indicator, such as a group jumper, to determinewhich group of frequencies to use, Group A or B. Examples of Group A andGroup B channel numbers and frequencies can be found in FIG. 8.

Step 1144′ proceeds to step 1146′ which makes a decision based uponwhether Group A or B is being used. If Group A is being used, step 1146′proceeds to step 1148′ which involves setting a base channel to theappropriate frequency for Group A. If Group B is to be used, step 1146′proceeds to step 1150′ which involves setting the base channel frequencyto a frequency for Group B.

After either Step 1148′ or step 1150′, the method proceeds to step 1152′which involves randomizing a reporting start time delay. For example,the randomization can be achieved by multiplying the lowest nibble ofthe serial number of monitoring and control unit 510 by 50 and using theresulting value, x, as the number of milliseconds for the reportingstart time delay.

The method proceeds from step 1152′ to step 1154′ which involves waitingx number of seconds as determined in step 1152′.

The method proceeds from step 1154′ to step 1156′ which involves settinga value z=0, where the value z represents an offset from the basechannel number set in step 1148′ or 1150′. Step 1156′ proceeds to step1158′ which determines whether the count equals 1. If the count equals1, the method proceeds from step 1158′ to step 1172′ which involvestransmitting the packet on a channel determined from the base channelfrequency selected in either step 1148′ or step 1150′ plus the channelfrequency offset selected in step 1156′.

If the count is not equal to 1, then the method proceeds from step 1158′to step 1160′ which involves determining whether the count is equal toN, where N represents the maximum number of packet transmissions. If thecount is equal to N, then the method proceeds from step 1160′ to step1172′ which involves transmitting the packet on a channel determinedfrom the base channel frequency selected in either step 1148′ or step1150′ plus the channel number offset selected in step 1156′.

If the count is not equal to N, indicating that the count is a valuebetween 1 and N, then the method proceeds from step 1160′ to step 1162′which involves reading a real time counter (RTC) which may be located inprocessing and sensing unit 412.

The method proceeds from step 1162′ to step 1164′ which involvescomparing the RTC value against a maximum value, for example, a maximumvalue of 152. If the RTC value is greater than or equal to the maximumvalue, then the method proceeds from step 1164′ to step 1166′ whichinvolves waiting x seconds and returning to step 1162′.

If the value of the RTC is less than the maximum value, then the methodproceeds from step 1164′ to step 1168′ which involves setting a value yequal to a value indicative of the channel number offset. For example, ycan be set to an integer of the real time counter value divided by 8, sothat Y value would range from 0 to 18.

The method proceeds from step 1168′ to step 1170′ which involvescomputing a frequency offset value z from the channel number offsetvalue y. For example, if a 25 KHz channel is being used, then z is equalto y times 25 KHz.

The method then proceeds from step 1170′ to step 1172′ which involvestransmitting the packet on a channel determined from the base channelfrequency selected in either step 1148′ or step 1150′ plus the channelfrequency offset computed in step 1170′.

The method proceeds from step 1172′ to step 1174′ which involvesincrementing the count value. The method proceeds from step 1174′ tostep 1176′ which involves comparing the count value to a value N+1 whichis related to the maximum number of transmissions for each packet. Ifthe count is not equal to N+1, the method proceeds from step 1176′ backto step 1154′ which involves waiting x number of milliseconds. If thecount is equal to N+1, the method proceeds from step 1176′ to the endblock 1178′.

The method shown in FIG. 11E is similar to that shown in FIG. 11D, butdiffers in that it requires the first and the Nth transmission to occurat the base frequency rather than a randomly selected frequency.

Although the above figures show numerous embodiments of the invention,it is well known to those skilled in the art that numerous modificationscan be implemented.

For example, FIG. 4 shows a light monitoring and control unit 310 inwhich there is no light sensor but rather an RX unit 416 for receivingcontrol information. Light monitoring and control unit 310 may be usedin an environment in which a centralized control system is preferred.For example, instead of having a decentralized light sensor at everylocation, light monitoring and control unit 310 of FIG. 4 allows for acentralized control mechanism. For example, RX unit 416 could receivecentralized energize/deenergize signals which are sent to all of thestreet lamp assemblies in a particular geographic region.

As another alternative, if lamp monitoring and control unit 310 of FIG.4 contains no RX unit 416, the control functionality can be builtdirectly in the processing and sensing unit 412. For example, processingand sensing unit 412 may contain a table with a listing of sunrise andsunset times for a yearly cycle. The sunrise and sunset times could beused to energize and deenergize the lamp without the need for either RXunit 416 or light sensor 518.

The foregoing embodiments are merely exemplary and are not to beconstrued as limiting the present invention. The present teaching can bereadily applied to other types of apparatuses. The description of thepresent invention is intended to be illustrative, and not to limit thescope of the claims. Many alternatives, modifications, and variationswill be apparent to those skilled in the art.

1. A system, comprising: a plurality of fixed transmit/receive unitseach having an antenna and capable of transmitting and receiving digitalpackets of information; at least one remote transmitting and receivingunit with a remote antenna capable of communicatively coupling to atleast one of said plurality of fixed transmit/receive units via saiddigital packets of information.